There is a variety of apparatus which is intended for use underwater and which includes electric circuitry that must be switched by an underwater operator while the apparatus is immersed. Examples include cameras, electronic measuring instruments, electrically controlled tools, underwater communications equipment, and other apparatus. To provide a switch that can be easily operated in the underwater environment and which does not involve risk that water will find its way into the apparatus, has proven to be a troublesome task. One approach employs a mechanical switch having moving parts that can be actuated from the exterior of the housing of an underwater apparatus. That approach requires the use of seals around the switch actuator of the use of boots or flexible, or pliant, housing wall sections which permit operation of switch actuators mounted within the housing. Even in the latter case, a sealing means of some kind is required around the boots and rubber covered wall openings, and the like. While the sealing problem is less severe than in the case of a movable actuator that extends through the case wall, pliant and resilient boots and covers tend to deteriorate and crack after a short time, especially in the case of units that are taken in and out of salt water frequently.
An alternative to such mechanical switching is to employ a sensor of some kind whose output is electrical in response to a condition that can be created selectively underwater by the user. Examples include proximity sensors using a change in capacitance, a very difficult approach in electrically conductive salt water, and voice actuated switching. Voice actuated switching is practical, especially for underwater communication equipment, but it presents problems in noisy environments.
Despite past efforts there has been a continuing need for low cost underwater switching apparatus that is reliable in both fresh and salt water and requires little or no maintenance.